Improved Estimation of Left Ventricular Volume from Electric Field Modeling

Area of Science:

• Biomedical Engineering
• Medical Devices
• Electrical Engineering

Background:

• Accurate volume measurement is crucial for optimizing left ventricular assist device (LVAD) therapy and patient demand quantification.
• Existing bioimpedance methods for estimating ventricular radius from conductance lack accuracy and require extensive calibration.
• Leveraging the LVAD platform for in-situ bioimpedance measurements could eliminate the need for additional implants.

Purpose of the Study:

• To develop and validate novel analytical methods for estimating left ventricular radius from bioimpedance conductance.
• To improve the accuracy and precision of radius estimation compared to established methods like Wei's.
• To assess the feasibility of using LVADs for non-invasive bioimpedance measurements within the ventricle.

Main Methods:

• Developed two analytical calculation methods based on electric field theory to estimate left ventricular radius from conductance.
• Incorporated dielectric properties of tissue, electric field refraction, and measurement-induced field changes into the models.
• Validated methods using glass containers of varying radii and in-vitro models mimicking left ventricular geometry and conductivity.

Main Results:

• The proposed analytical methods demonstrated higher accuracy and precision in estimating radii compared to Wei's method.
• Excellent performance was observed in glass cylinders across a range of radii, with low bias (1.66%-2.48%) and limits of agreement (<16.33%).
• The methods achieved reliable results without requiring geometry-specific calibration.

Conclusions:

• The novel analytical methods provide a more accurate and precise approach to estimating left ventricular radius from bioimpedance data.
• These findings support the potential of using LVADs as a platform for in-situ bioimpedance measurements for improved patient monitoring.
• The developed methods offer a calibration-free solution, simplifying clinical application and enhancing LVAD therapy management.